Human risk assessment of ash soil after 2020 wildfires in Pantanal biome (Brazil)

Abstract

Wildfires have increased in the last years and, when caused by intentional illegal burnings, are frequently run out of control. Wildfire has been pointed out as an important source of polycyclic aromatic hydrocarbons (PAHs) and trace elements (TEs) - such as, As, Ni, and Pb - to environmental compartments, and thus may pose a risk to human health and to the ecosystem. In 2020, the Brazilian biome, Pantanal, faced the largest losses by wildfires in the last 22 years. Ashes from the topsoil layer in Pantanal were collected after these wildfires at 20 sites divided into the sediment, forest, PF, PS, and degraded sites. Toxicity and associated risks for human health were also evaluated. The areas highly impacted by wildfires and by artisanal gold mining activities showed higher concentrations for TEs and PAHs than the protected areas. Pb varied from 8 ± 4 to 224 ± 81 mg kg^-1, and total PAH concentration ranged between 880 ± 314 and 1350 ± 70 ng g^-1, at sites impacted by anthropogenic activities. Moreover, health risk assessments for TE and PAH indicated a potentially great risk for children and adults, via ingestion, inhalation, and dermal pathway. The carcinogenic risks exceeded reference values, for both TE and PAH, suggesting harmful conditions, especially for vulnerable groups, such as children and the elderly.

Supplementary information: The online version contains supplementary material available at 10.1007/s11869-022-01248-2.

Keywords: Pantanal; Polycyclic aromatic hydrocarbons; Risk assessment; Trace elements; Wildfire.

Fig. 1

Map of sampling sites in Pantanal

Fig. 2

Boxplot and bar plots of element concentration to sediment and forest sites, protected sediment and forest areas, and degraded sites comparing ash contents to the criteria obtained from the literature. The United States Environmental Protection Agency (EPA), plant–avian–mammalian screening level (red line), and the Canadian Council of Ministers of the Environment (CCME), and soil quality guideline for agricultural and residential land use (blue line)

Fig. 2

Boxplot and bar plots of element concentration to sediment and forest sites, protected sediment and forest areas, and degraded sites comparing ash contents to the criteria obtained from the literature. The United States Environmental Protection Agency (EPA), plant–avian–mammalian screening level (red line), and the Canadian Council of Ministers of the Environment (CCME), and soil quality guideline for agricultural and residential land use (blue line)

Fig. 3

PCA variables for trace elements (a) and cluster plot for sampling sites (b) related to ash samples collected at Pantanal

Fig. 4

Total of PAHs at sampling points in the present study and previous studies around the world. From ∑15PAH (Portugal) to ∑24PAH (Brazilian Amazon)

Fig. 5

PAH contribution in ash samples at Pantanal sites

Fig. 6

Incremental lifetime cancer risk (ILCR) for ingestion, dermal and total exposure, and carcinogenic B[a]P equivalent (BaP_EQ) concentration at all sites in Pantanal ash samples